To determine whether ATM serine-1981 phosphorylation disrupts ATM identification by ab32420, H460 lung adenocarcinoma cells stably expressing either an shRNA that targets ATM or a scrambled shRNA [27], were treated with KU55933, a small molecule ATM kinase inhibitor [28], and exposed to 2 Gy IR. The gene discussed is ATM; the disease is lung adenocarcinoma.